Douglas Alexander was a student at The Langham. He had remained a background character since his debut in the first season until playing a more prominent role during the fifth season, until his eventual death near the end of the eighteenth season.
- "Cold Lazarus" - Douglas's debut; he is seen in the control room.
- "Thor's Hammer" - Seen monitoring the M.A.L.P.
- "The Torment of Tantalus" - Seen in the control room.
- "Daimen" - Seen in Mr. Brown's classroom.
- "Within the Serpent's Grasp" - Douglas drives the M.A.L.P. around the area in which Mecha-Streisand is wrecking havoc.
- "The Serpent's Lair" - Seen in the hallways.
- "Chickenlover" - Seen at the petting zoo.
- "Thor's Chariot" - Seen eating in the cafeteria.
- "The Tok'ra, Part 1" - Seen in Mr. Brown's classroom.
- "The Fifth Race" - Seen in the control room.
- "Rainforest Shmainforest - Seen on the Getting Gay with Kids tour.
- "Tweek vs. Toad" - Seen watching the fight.
- "Archen" - Seen in Mr. Brown's classroom.
- "Nemesis" - Seen in the the background in the school hallways.
- "Small Victories" - Seen in the background of the Control Room.
- "Life Of Crime" - Seen at Rob's Trial.
- "The Light" - Seen in the background of Mr. Brown's Class.
- "Prototype" - Speaking debut; Informs Mr. Mandelson of Lance Patrick's location.
- "48 Hours" - Seen in the control room.
- "Toad Stands By" - Seen in the background in the school hallways.
- "Meridian" - Seen in the background of Mr. Brown's Class and the school hallways.
- "Revelations" - Seen in the background of Mr. Brown's Class.
- "The Other Guys" - Seen eating lunch.
- "Prometheus" - One of the candidates for the new 4th member of Puff's Team; He was eliminated in the fifth round.
- "Unnatrual Selection" - Joins his friends on the fight over the Replicators.
- "Around The Whirlpool" - Partners with Lucy.
- "EOS" - seen with Clyde's gang.
- "Heroes, Part 2" - Douglas' final appearance; he is killed by a rogue Jaffa whilst trying to defend an injured Simon Wells.
Video Games (Non-Canon)
Douglas is an unlockable character in the game. He can be unlocked at Kalahari Desert, where his Krypt Key can be found in a treasure chest hidden inside a rock bed close to the entrance to the underground lair in the level.
Italic denotes deceased character.